I met someone yesterday that has a Zenith that he landed in a field three years ago because of a fuel management issue (somehow drained the header tank into the wing tank while flying). There was no damage and the engine was fine the last it ran, but he never preserved the engine correctly. He just drained the fuel out of the plane and put it in storage.
I told him that the best thing to do would be to tear the engine down and inspect it or at least find someone with a borescope to look inside for rust before he tries to start it. If he decides that he just wants to just take a chance at spinning a frozen bearing or gouging his pistons on rusty cylinders what should be done before he starts the engine besides changing the oil and pulling off the valve covers to inspect what he can see? Is there any kind of oil or something that is recommended for spraying in the cylinders first or something that he should pump through the oil system to clean it out first?
